/*
Copyright 2006 Jerry Huxtable

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
using System;
using GeoAPI.Geometries;
using Proj4Net.Utility;

namespace Proj4Net.Projection
{


    public class RobinsonProjection : PseudoCylindricalProjection
    {

        private static readonly double[] X = new double[] {
		1,	-5.67239e-12,	-7.15511e-05,	3.11028e-06,
		0.9986,	-0.000482241,	-2.4897e-05,	-1.33094e-06,
		0.9954,	-0.000831031,	-4.4861e-05,	-9.86588e-07,
		0.99,	-0.00135363,	-5.96598e-05,	3.67749e-06,
		0.9822,	-0.00167442,	-4.4975e-06,	-5.72394e-06,
		0.973,	-0.00214869,	-9.03565e-05,	1.88767e-08,
		0.96,	-0.00305084,	-9.00732e-05,	1.64869e-06,
		0.9427,	-0.00382792,	-6.53428e-05,	-2.61493e-06,
		0.9216,	-0.00467747,	-0.000104566,	4.8122e-06,
		0.8962,	-0.00536222,	-3.23834e-05,	-5.43445e-06,
		0.8679,	-0.00609364,	-0.0001139,	3.32521e-06,
		0.835,	-0.00698325,	-6.40219e-05,	9.34582e-07,
		0.7986,	-0.00755337,	-5.00038e-05,	9.35532e-07,
		0.7597,	-0.00798325,	-3.59716e-05,	-2.27604e-06,
		0.7186,	-0.00851366,	-7.0112e-05,	-8.63072e-06,
		0.6732,	-0.00986209,	-0.000199572,	1.91978e-05,
		0.6213,	-0.010418,	8.83948e-05,	6.24031e-06,
		0.5722,	-0.00906601,	0.000181999,	6.24033e-06,
		0.5322, 0, 0, 0d
	};

        private static readonly double[] Y = new double[] {
		0,	0.0124,	3.72529e-10,	1.15484e-09,
		0.062,	0.0124001,	1.76951e-08,	-5.92321e-09,
		0.124,	0.0123998,	-7.09668e-08,	2.25753e-08,
		0.186,	0.0124008,	2.66917e-07,	-8.44523e-08,
		0.248,	0.0123971,	-9.99682e-07,	3.15569e-07,
		0.31,	0.0124108,	3.73349e-06,	-1.1779e-06,
		0.372,	0.0123598,	-1.3935e-05,	4.39588e-06,
		0.434,	0.0125501,	5.20034e-05,	-1.00051e-05,
		0.4968,	0.0123198,	-9.80735e-05,	9.22397e-06,
		0.5571,	0.0120308,	4.02857e-05,	-5.2901e-06,
		0.6176,	0.0120369,	-3.90662e-05,	7.36117e-07,
		0.6769,	0.0117015,	-2.80246e-05,	-8.54283e-07,
		0.7346,	0.0113572,	-4.08389e-05,	-5.18524e-07,
		0.7903,	0.0109099,	-4.86169e-05,	-1.0718e-06,
		0.8435,	0.0103433,	-6.46934e-05,	5.36384e-09,
		0.8936,	0.00969679,	-6.46129e-05,	-8.54894e-06,
		0.9394,	0.00840949,	-0.000192847,	-4.21023e-06,
		0.9761,	0.00616525,	-0.000256001,	-4.21021e-06,
		1, 0, 0, 0
	};

        private const int NODES = 18;
        private const double FXC = 0.8487;
        private const double FYC = 1.3523;
        private const double C1 = 11.45915590261646417544;
        private const double RC1 = 0.08726646259971647884;
        private const double ONEEPS = 1.000001;
        private const double EPS = 1e-8;

        public RobinsonProjection()
        {
        }

        private double poly(double[] array, int offset, double z)
        {
            return (array[offset] + z * (array[offset + 1] + z * (array[offset + 2] + z * array[offset + 3])));
        }

        public override Coordinate Project(double lplam, double lpphi, Coordinate xy)
        {
            double phi = Math.Abs(lpphi);
            int i = (int)Math.Floor(phi * C1);
            if (i >= NODES)
                i = NODES - 1;
            phi = ProjectionMath.ToDegrees(phi - RC1 * i);
            i *= 4;
            xy.X = poly(X, i, phi) * FXC * lplam;
            xy.Y = poly(Y, i, phi) * FYC;
            if (lpphi < 0.0)
                xy.Y = -xy.Y;
            return xy;
        }

        public override Coordinate ProjectInverse(double x, double y, Coordinate lp)
        {
            int i;
            double t, t1;

            lp.X = x / FXC;
            lp.Y = Math.Abs(y / FYC);
            if (lp.Y >= 1.0)
            {
                if (lp.Y > 1.000001)
                {
                    throw new ProjectionException();
                }
                else
                {
                    lp.Y = y < 0.0 ? -ProjectionMath.PiHalf : ProjectionMath.PiHalf;
                    lp.X /= X[4 * NODES];
                }
            }
            else
            {
                for (i = 4 * (int)Math.Floor(lp.Y * NODES); ; )
                {
                    if (Y[i] > lp.Y)
                        i -= 4;
                    else if (Y[i + 4] <= lp.Y)
                        i += 4;
                    else
                        break;
                }
                t = 5.0 * (lp.Y - Y[i]) / (Y[i + 4] - Y[i]);
                double Tc0 = Y[i];
                double Tc1 = Y[i + 1];
                double Tc2 = Y[i + 2];
                double Tc3 = Y[i + 3];
                t = 5.0 * (lp.Y - Tc0) / (Y[i + 1] - Tc0);
                Tc0 -= lp.Y;
                for (; ; )
                { // Newton-Raphson
                    t -= t1 = (Tc0 + t * (Tc1 + t * (Tc2 + t * Tc3))) / (Tc1 + t * (Tc2 + Tc2 + t * 3.0 * Tc3));
                    if (Math.Abs(t1) < EPS)
                        break;
                }
                lp.Y = ProjectionMath.ToRadians(5 * i + t);
                if (y < 0.0)
                    lp.Y = -lp.Y;
                lp.X /= poly(X, i, t);
            }
            return lp;
        }

        public override Boolean HasInverse
        {
            get { return true; }
        }

        public override String ToString()
        {
            return "Robinson";
        }

    }
}